An amputee is a person who has lost part of an extremity or limb such as a leg or arm. That which remains is commonly referred to as a residual limb. Residual limbs come in various sizes and shapes with respect to the stump. For instance, new amputations are often slightly bulbous or cylindrical in shape while older amputations that have atrophied are generally more conical in shape. Residual limbs may also be characterized by their various individual configurations including the volume and shape of a stump, bony prominence, uneven limb volume or soft tissue configurations. For example, a leg severed above the knee generally terminates in a fleshy stump while a leg severed below the knee generally terminates in a bony stump.
More particularly, referring to FIG. 1, a below the knee residual limb 18 is shown and described as a leg 20 having been severed below the knee terminating in a stump 22 also referred to as a leg terminus. In this case stump 22 is formed by the severed tibia 28 and fibula 30 and the smaller, less voluminous muscles of the lower leg. Thus, a below the knee residual limb 18 has its stump 22 generally characterized as being a more bony structure while an above the knee residual limb (not shown) is characterized as including more soft tissue.
Artificial limbs typically used by a leg amputee have sockets to put the amputee's stump into. There are generally two categories of sockets. There are hard sockets wherein the stump goes right into the socket actually touching the socket wall without any type of liner or stump sock. Another category of sockets is a socket that utilizes a liner or insert. Both categories of sockets typically are opened ended sockets having a hollow chamber in the bottom.
In the past, most artificial limbs were suspended from the amputee's body by some form of pulley, belt or strap suspension often used with various harnesses, leather lacers or lacings. However, these types of suspension systems are bulky and uncomfortable to wear, and when the residual limb was a leg severed above the knee, the socket had to include an ischial flare which only increased bulk and discomfort. Another method of suspending artificial limbs required the amputee to use a latex rubber tube formed into a rubber-like sleeve which would be rolled on over both the top of the artificial limb and onto the amputee's thigh. In some instances, a negative pressure system was used in combination with the rubber sleeve which required forming a negative pressure chamber between the leg and socket using a vacuum pump. The sleeve acted as a seal between the limb and socket thereby suspending the socket from the limb. However, since the seal was formed on the outside of the socket it was prone to puncturing which resulted in suction loss within the sealed chamber and detachment of the socket from the residual limb.